The invention concerns the field of hydraulic brake architectures for aircrafts for braking at least one wheel of the aircraft.
There is known a brake architecture for aircraft wheels of the type described with reference to FIG. 1. This prior art architecture comprises:                at least one brake provided with at least one hydraulic actuator for braking the wheel,        at least one pressure source Alim adapted to deliver a hydraulic fluid at high pressure; and        a normal braking hydraulic circuit C1.        
This normal braking hydraulic circuit C1 includes at least one pressure control servo valve BCV including:                a supply port P connected (directly or indirectly) to the pressure source Alim;        a return port R;        a utilization port U connected to the braking hydraulic actuator; and        a mobile slide valve adapted to be commanded to associate the utilization port U with the supply port P and the return port R so that the pressure in the utilization port is equal to a pressure set point.        
The FIG. 1 brake architecture further includes a parking hydraulic circuit C2 including a parking brake valve PkBV having an outlet port Ps1 adapted to be connected selectively either to the pressure source Alim or to a return circuit CR at a pressure that is low relative to said high pressure.
The outlet of the parking brake valve and the outlet of the servo valve here form the inlets of a shuttle valve the outlet of which is connected to the braking actuator.
Accordingly, for parking braking, it suffices to manoeuvre the parking brake valve to connect its outlet to the supply source. The high pressure is thus communicated to the inlet of the shuttle valve and is transmitted to the braking actuator.
The pressure of the low-pressure fluid in the return circuit is typically of the order of 5 bar. This positive pressure in the return circuit CR enables reduction of the risk of gas appearing in the return circuit. The pressure of the high-pressure fluid from the supply source Alim is typically 206 bar.
A drawback of such a prior art brake architecture is to have part of the hydraulic energy produced at the level of the high-pressure source Alim that is lost in the form of hydraulic leaks toward the return circuit CR.
In particular, during normal braking phases (or parking braking) during which the pressure source is unavailable, the circuit C1 or the circuit C2 is pressurized by an accumulator. Now, because of leaks from the equipments of the circuit C1, the accumulator is eventually emptied and no longer able to provide a sufficient pressure level after a few actuations of the brakes.